Dear Lab Tests OnlineAU community,
You are invited to participate in a survey focused on users’ perceptions of the Lab Tests Online Australasia website which we have developed in collaboration with Curtin University. Your feedback will assist us to improve the website and better support the general public’s and health professionals’ understanding about pathology lab tests. This survey should take about 5-7 minutes to complete. Participation is completely voluntary and all the information you provide will be anonymous.
Lab Test OnlineAU Team
LDH; lactate dehydrogenase; total LD; total LDH; LD isoenzymes; LDH isoenzymes
To help identify tissue cell damage in the body, and to monitor its progress
Along with other tests, when your doctor suspects that you have an acute or chronic condition that is causing tissue or cellular destruction and they want to identify and monitor the problem
A blood sample drawn from a vein in the arm
Lactate dehydrogenase (LD) is an enzyme that is found in cells throughout the body.
Only a small amount of LD is usually detectable in the blood. However, when cells are damaged or destroyed, they release LD into the bloodstream, causing blood levels to rise. For this reason, LD is used as a general marker of injury to cells. This also happens when blood cells are destroyed in the bloodstream, such as in a form of anaemia known as haemolytic anaemia.
In the past, special tests were performed to work out which type of tissue the LD was released from. These tests, known as `LD isoenzymes’ are not performed routinely anymore because there are more specific tests available.
A blood sample is obtained by inserting a needle into a vein in the arm.
No test preparation is needed.
The main use for LD is as a general indication of cell damage, including muscle damage, liver damage, blood cell damage and cancers. In the past, LD was used to help diagnose and monitor myocardial infarctions (heart attacks) but it has been replaced by a better test, troponin (more specific and sensitive to heart tissue injury than LD).
In people with progressive conditions, including melanoma, LD can be tested at regular intervals to monitor the progress of the condition.
LD may be used as a screening test when some kind of cellular or tissue damage is suspected. If the LD is high other, more specific tests such as CK, ALT and AST can be used to help pinpoint the organs involved. Once the problem is diagnosed, LD levels may be tested at regular intervals to monitor its progress.
LD levels can also occasionally be ordered when someone has experienced muscle trauma or injury. They can also be ordered when someone has signs and symptoms of haemolytic anaemia.
LD testing may be ordered on a regular basis when someone has been diagnosed with cancer.
High levels of LD usually indicate some type of tissue damage. Usually LD levels rise as the cell destruction begins, peak after some time and then begin to fall. As an example, when someone has a heart attack, blood levels of total LD rise within 24 to 48 hours, peak in two to three days and return to normal in 10 to 14 days.
Elevated levels of LD may be seen with:
With some chronic and progressive conditions, and some drugs, moderately elevated LD levels may persist.
Low levels of LD do not usually indicate a problem.
Many things can affect LD results that are not necessarily a cause for concern. For example:
CK (creatine kinase), CK-MB, troponin, myoglobin, AST, ALT
Conditions: Heart disease, heart attack, anaemia
RCPA Manual: Lactate dehydrogenase
Last Review Date: November 10, 2018